MR relaxation times of agar‐based tissue‐mimicking phantoms

Journal of Applied Clinical Medical Physics, Год журнала: 2022, Номер 23(5)

Опубликована: Апрель 12, 2022

Agar gels were previously proven capable of accurately replicating the acoustical and thermal properties real tissue widely used for construction tissue-mimicking phantoms (TMPs) focused ultrasound (FUS) applications. Given current popularity magnetic resonance-guided FUS (MRgFUS), we have investigated MR relaxation times T1 T2 different mixtures agar-based phantoms. Nine TMPs constructed containing agar as gelling agent various concentrations silicon dioxide evaporated milk. An phantom doped with wood powder was also evaluated. A series images acquired in a 1.5 T scanner mapping. predominantly affected by varying concentrations. trend toward decreasing an increasing concentration milk observed. The addition decreased both pure gels. proposed great potential use continuously emerging MRgFUS technology. several body tissues can be mimicked adjusting ingredients, thus enabling more accurate realistic studies.

Язык: Английский

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Robotic system for top to bottom MRgFUS therapy of multiple cancer types

International Journal of Medical Robotics and Computer Assisted Surgery, Год журнала: 2022, Номер 18(2)

Опубликована: Янв. 7, 2022

A robotic system for Magnetic Resonance guided Focussed Ultrasound (MRgFUS) therapy of tumours in the breast, bone, thyroid, and abdomen was developed.A special C-shaped structure designed to be attached table conventional magnetic resonance imaging (MRI) systems carrying 4 computer-controlled motion stages dedicated positioning a 2.75 MHz spherically focussed transducer relative patient placed supine position. The developed evaluated its MRI compatibility heating abilities agar-based phantoms freshly excised tissue.Compatibility with clinical high-field scanner demonstrated. FUS phantom successfully monitored by thermometry without any evidence magnetically induced phenomena. Cigar-shaped discrete lesions well-defined areas overlapping were inflicted tissue movement along grid patterns.The MRgFUS proven safe efficient ex-vivo feasibility studies.

Язык: Английский

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Tumor phantom model for MRI‐guided focused ultrasound ablation studies

Medical Physics, Год журнала: 2023, Номер 50(10), С. 5956 - 5968

Опубликована: Май 24, 2023

The persistent development of focused ultrasound (FUS) thermal therapy in the context oncology creates need for tissue-mimicking tumor phantom models early-stage experimentation and evaluation relevant systems protocols.This study presents a tumor-bearing tissue model testing magnetic resonance imaging (MRI)-guided FUS (MRgFUS) ablation protocols equipment based on MR thermometry.Normal was mimicked by pure agar gel, while simulator differentiated from surrounding material including silicon dioxide. characterized terms acoustic, thermal, MRI properties. US, MRI, computed tomography (CT) images were acquired to assess contrast between two compartments. phantom's response heating investigated performing high power sonications with 2.4 MHz single element spherically ultrasonic transducer 3T scanner.The estimated properties fall within range literature-reported values soft tissues. inclusion dioxide offered excellent visualization CT. thermometry revealed temperature elevations levels clear evidence larger heat accumulation owing dioxide.Overall, findings suggest that proposed constitutes simple inexpensive tool preclinical MRgFUS studies, potentially other image-guided applications upon minimal modifications.

Язык: Английский

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Cryostructuring of Polymeric Systems: 64. Preparation and Properties of Poly(vinyl alcohol)-Based Cryogels Loaded with Antimicrobial Drugs and Assessment of the Potential of Such Gel Materials to Perform as Gel Implants for the Treatment of Infected Wounds

Gels, Год журнала: 2023, Номер 9(2), С. 113 - 113

Опубликована: Янв. 28, 2023

Physical macroporous poly(vinyl alcohol)-based cryogels formed by the freeze-thaw technique without use of any foreign cross-linkers are significant interests for biomedical applications. In present study, such gel materials loaded with antimicrobial substances were prepared and their physicochemical properties evaluated followed an assessment potential to serve as drug carriers that can be used implants treatment infected wounds. The antibiotic Ceftriaxone antimycotic Fluconazole agents. It was shown additives caused up-swelling effects respect cryogel matrix some decrease in its heat endurance but did not result a substantial change strength. With that, release from vehicle occurred diffusion restrictions, which demonstrated both spectrophotometric recording microbiological agar technique. turn, vivo biotesting drug-loaded also showed these able function rather efficient injected artificially model wounds laboratory rabbits. These results confirmed promising similar implants.

Язык: Английский

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Focused Ultrasound Sonications of Tumor Model in Head Phantom under MRI Monitoring: Effect of Skull Obstruction on Focal Heating

Journal of Medical Physics, Год журнала: 2025, Номер 50(1), С. 38 - 45

Опубликована: Янв. 1, 2025

This study presents the outcomes of a series magnetic resonance imaging (MRI)-guided focused ultrasound (MRgFUS) sonications performed on an anatomically accurate head phantom with embedded tumor simulator to evaluate effectiveness partial and complete ablation obstruction from thin polymer skull mimics. The was subjected single grid using single-element concave transducer integrated MRI-compatible (FUS) robotic system. All experiments were carried out in high-field MRI scanner utilizing proton frequency thermometry T2-weighted (T2-W) turbo spin echo (TSE) induced thermal effects. FUS transmission through 1-mm thick three-dimensional-printed mimics compared unobstructed sonication circular aperture model. T2-W TSE demonstrated sharp contrast between hyperintense lesions. Complete coverage achieved robotic-assisted without mimic, as well resin mimic intervening beam. With lowest attenuation among tested polymers, resulted approximately 20% reduction focal temperature change sonication, yet still facilitated beam focusing, raising ablative levels. provides preliminary evidence for potential application biocompatible implant temporarily replace portion facilitating MRgFUS inoperable tumors transducer. tumor-embedded proven effective testing oncological protocols equipment.

Язык: Английский

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Development of estimation method for T1 and T2 values using the relaxivity of contrast agent and coagulant for a magnetic resonance imaging phantom

Radiological Physics and Technology, Год журнала: 2025, Номер unknown

Опубликована: Март 23, 2025

Язык: Английский

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Focused ultrasound heating in brain tissue/skull phantoms with 1 MHz single-element transducer

Journal of Ultrasound, Год журнала: 2023, Номер 27(2), С. 263 - 274

Опубликована: Июль 30, 2023

Abstract Purpose The study aims to provide insights on the practicality of using single-element transducers for transcranial Focused Ultrasound (tFUS) thermal applications. Methods FUS sonications were performed through skull phantoms embedding agar-based tissue mimicking gels a 1 MHz spherically focused transducer. 3D printed with Acrylonitrile Butadiene Styrene (ABS) and Resin thermoplastics having exact bone geometry healthy volunteer. temperature field distribution during after heating was monitored in 3 T Magnetic Resonance Imaging (MRI) scanner MR thermometry. effect skull’s thickness intracranial investigated. Results A single sonication at focal acoustic intensities close 1580 W/cm 2 60 s free heated up agar phantom ablative temperatures reaching about 90 °C (baseline 37 °C). ABS strongly blocked ultrasonic waves, resulting zero increase within phantom. Considerable achieved skull, but it remained hyperthermia levels. Conversely, tFUS mm showed enhanced penetration heating, 70 °C. Conclusions demonstrated poorer performance terms compared owing its higher attenuation porosity. thin provided an efficient window delivering deep areas. results such studies could be particularly useful accelerating establishment wider range

Язык: Английский

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Relaxation measurements of an MRI system phantom at low magnetic field strengths

Magnetic Resonance Materials in Physics Biology and Medicine, Год журнала: 2023, Номер 36(3), С. 477 - 485

Опубликована: Май 20, 2023

Temperature controlled T1 and T2 relaxation times are measured on NiCl2 MnCl2 solutions from the ISMRM/NIST system phantom at low magnetic field strengths of 6.5 mT, 64 mT 550 mT.The were five samples with increasing concentrations MnCl2. All scanned sample temperatures ranging 10 °C to 37 °C.The showed little change in strength, both decreased temperature. The an increase a decrease increased temperature.The rates arrays investigated compared results clinical 1.5 T 3.0 T. measurements can be used as benchmark for MRI functionality stability, especially when systems taken out radiology suite or laboratory into less traditional environments.

Язык: Английский

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Silicone‐based materials with tailored MR relaxation characteristics for use in reduced coil visibility and in tissue‐mimicking phantom design

Medical Physics, Год журнала: 2023, Номер 50(6), С. 3498 - 3510

Опубликована: Фев. 4, 2023

The development of materials with tailored signal intensity in MR imaging is critically important both for the reduction from non-tissue hardware, as well construction tissue-mimicking phantoms. Silicone-based phantoms are becoming more popular due to their structural stability, stretchability, longer shelf life, and ease handling, application dynamic physiology motion. Moreover, silicone can be also used design stretchable receive radio-frequency (RF) coils.

Язык: Английский

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High-fidelity anatomical phantoms for MRI practical training

Physica Medica, Год журнала: 2024, Номер 127, С. 104832 - 104832

Опубликована: Окт. 19, 2024

Practical MRI training is essential for bridging the gap between complex theoretical knowledge and clinical applications. Traditional phantoms used in MRI, such as ACR phantoms, are valuable illustrating system characterization methods but often lack anatomical complexity required realistic training. This study presents development of high-fidelity designed specifically practical These replicate key structures tissue contrasts head, offering a more experience healthcare students medical imaging staff (radiologists, physicists, radiographers). We focused on head region, creating from reference T1-weighted slices using computer-aided design (CAD) software to detailed structures. were 3D printed filled with tissue-mimicking gels. acquisitions performed 1.5T system. The resulting images demonstrated high fidelity contrasts. allow effective demonstration impact parameter modifications aid structure recognition. While technical improvements needed ensure long-term stability accurate relaxometric properties, these hold significant potential enhancing education sequences evaluations. approach can be extended other regions, further supporting optimization sequences.

Язык: Английский

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